Interfacial properties of model membranes and plasma lipoproteins containing ether lipids.
Interfacial properties of model membranes and plasma lipoproteins containing ether lipids.
复制标题
模型膜和含有醚脂质的血浆脂蛋白的界面特性。
DOI：
10.1021/bi00345a033
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发表时间：
1985
期刊：
影响因子：
2.9
通讯作者：
Pownall,HJ
中科院分区：
文献类型：
--
作者：
Massey,JB;She,HS;Pownall,HJ
以6-丙酰基-2-二甲氨基萘（Prodan）和芘为极性敏感荧光探针，研究了合成的酯型和醚型磷脂酰胆碱（PC）的界面性质。磷脂基质的物理状态由1，6-二苯基-1，3，5-己三烯（DPH）的荧光偏振确定。研究了超声处理形成的单双层磷脂囊泡和模型高密度脂蛋白。根据一些光谱和热力学标准，PC及其醚类似物的界面区域是相似的。Prodan在模型脂蛋白或单双层囊泡中的荧光性质与磷脂脂肪酰基链长和极性头基以及磷脂中醚键取代酯键无关。光谱位移主要与磷脂的物理状态有关。Prodan的发射光谱在从水转移到液晶磷脂时出现较短的波长，并且当脂质冷却到其凝胶相时进一步蓝移。模型高密度脂蛋白中胆固醇对Prodan发射光谱的影响是剂量依赖性的，并且在18 mol%胆固醇时，光谱与在纯凝胶相脂质中观察到的相似，并且与温度无关。Prodan荧光在醚-PC矩阵的量子产率是类似于在水中观察到的，而在酯-PC矩阵，它被增强了约5倍。Prodan的磷脂-水分配系数不依赖于1，2-二肉豆蔻酰基-n-甘油基-3-磷酸胆碱或1，2-十四烷基-n-甘油基-3-磷酸胆碱的物理状态。在醚和酯PC中，芘的振动带的增强比的变化对应于脂质相变。用醚基取代酯基后，芘的量子产率大大提高。在凝胶与液晶相的探针的光谱差异是一致的，在排斥或进入的水的界面区域，由于横向扩展的头部基团的差异。观察到的胆固醇效应与探针环境脱水一致。普罗丹，芘，和DPH在醚磷脂的量子产率降低表明，更大的水渗透创建一个疏水-亲水平衡的醚磷脂的界面，这是可比的酯磷脂。因此，通过界面疏水效应与磷脂表面结合的蛋白质和其他两亲物不应区分二酰基和二烷基甘油磷酸胆碱，而与磷脂-水界面结合的有解脂酶、脂质转移蛋白、载脂蛋白和某些膜结合蛋白。该区域的性质是初始关联、复合物的稳定性以及这些蛋白质在磷脂基质中的功能的关键决定因素。磷脂的界面区域的极性和介电常数与双层内部的极性和介电常数不同（Griffith等人，1974;施密特等人，1977; Ashcroft等人，一九八一年; Bellemare & Fragata，1980），并且已经提出脂质-水界面的极性或水合作用来调节蛋白质-磷脂缔合的热力学（Pownall等人，1981 b，1982 b; Mi-siorowski &威尔斯，1974）。此外，这些表面因子可能调节位于膜和脂蛋白中磷脂-水界面的蛋白质和其他两亲物的活性或亲脂性。我们已经研究了表面区域的性质...
The interfacial properties of synthetic ester and ether phosphatidylcholines (PCs) were investigated by using the polarity-sensitive fluorescent probes 6-propionyl-2-(dimethylamino) naphthalene (Prodan) and pyrene. The physical state of the phospholipid matrix was determined by fluorescence polarization of 1, 6-diphenyl-1, 3, 5-hexatriene (DPH). Single-bilayer phospholipid vesicles formed by sonication and model high-density lipoproteins were studied. On the basis of a number of spectroscopic and thermodynamic criteria, the interfacial regions of PCs and their ether analogues are similar. The fluorescence properties of Prodan in model lipoproteins or single-bilayer vesicles were independent of the phospholipid fatty acyl chain length and polar head group, as well as the substitution of ether linkage for ester bonds in the phospholipid. The spectral shifts correlated mainlywith the physical state of the phospholipid. The emission spectrum of Prodan appeared at shorter wavelengths upon transferfrom waterto liquid-crystalline phospholipidand blue shifted further when the lipid was cooled to its gel phase. The effect of cholesterol in model high-density lipoproteins on the emission spectrum of Prodan was dose dependent and, at 18 mol% cholesterol, the spectrum was similar to that observed in a pure gel-phase lipid and was independent of temperature. The quantum yield of Prodan fluorescence in an ether-PC matrix was similar to that observed in water, whereas in an ester-PC matrix it was enhanced by a factor of about 5. Phospholipid-water partition coefficients of Prodan were independent of the physical state of l, 2-dimyristoyl-j «-glycero-3-phosphocholine or 1, 2-tetradecyl-snglycero-3-phosphocholine. In ether and ester PCs, changes in the enhancement ratio of the vibronic bands of pyrene corresponded with the lipid-phase transition. The quantum yield of pyrene was greatly enhanced when an ester-PC matrix was replaced by an ether-PC matrix. Spectral differences of the probes in gel vs. liquid-crystalline phases are consistent with differences in exclusion or entry of water into the interfacial region due to lateral expansion of the head groups. The observed effects with cholesterol are consistent with dehydration of the probe environment. The decreased quantum yield of Prodan, pyrene, and DPH in ether phospholipids suggests that greater water penetration creates a hydrophobic-hydrophilic balance in the interface for ether phospholipids that is comparable to that of ester phospholipids. Therefore, proteins and other amphiphilesthat associate with the phospholipid surfaces via the interfacial hydrophobic effect should not distinguish between diacyl-and dialkylglycerophosphocholines.Ijipolytic enzymes, lipid transfer proteins, apolipoproteins, and certain membrane-bound proteins associate with the phospholipid-water interface. The properties of this region are key determinants of the initial association, the stability of the complex, and probably the function of these proteins in the phospholipid matrix. The polarity and dielectric con-stant of the interfacial region of phospholipids are distinct from those of the bilayer interior (Griffith et al., 1974; Schmidt et al., 1977; Ashcroft et al., 1981; Bellemare & Fragata, 1980), and the polarity or hydration of the lipid-water interface has been suggested to regulate the thermodynamics of protein-phospholipid association (Pownall et al., 1981b, 1982b; Mi-siorowski & Wells, 1974). In addition, these surface factors might modulate the activity or lipophilicity of proteins and other amphiphiles that locate at the phospholipid-water interface in membranes and lipoproteins. We have investigated the nature of the surface region of …